A mathematical model for estimating the zone of intense evaporation of gas condensate during emissions from shallow wells

Solbakov V.V., Zatsepa S.N., Ivchenko A.A.
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Safe carrying out of emergency recovery operations at emergency offshore gas condensate wells is possible when taking into account the hazardous factors that prevent anti-fontanning measures. One of such factors is the gassiness of the operation zone due to the release from the water column of a large amount of light, as compared to air, natural gas, as well as vapours of heavier components of gas condensate. To estimate the distribution of explosive concentration of petroleum product vapours in the near surface layer of the atmosphere, it is necessary to determine the characteristics of the source of the contamination. Based on the analysis of theoretical works concerning to the formation of the velocity field in the upper layer of the sea as a result of large amounts of gas coming to the surface, an analytical model is proposed to calculate the size of the area in which a significant amount of gas condensate coming to the surface is vaporised during accidents at shallow-water wells. The stationary regime of reservoir fluid flow during fountaining of offshore gas and oil wells with an underwater location of their mouths is considered. A low-parametric model of oil product evaporation from films of different thickness is constructed. It is shown that the size of the zone of intensive evaporation at shallow-water wells is determined by the volume flow of liquid fraction, its fractional composition and selected threshold for estimation of oil product vapour flow into the atmosphere. In the context of this work shallow water wells are wells with gas flow rate from 1 to 20 million cubic meters at sea depths of about 50–200 metres. In this case, the formation fluid jet from the wellhead on the seabed is transformed into a bubble plume, the stratification of the water column, typical for the summer-autumn period, does not limit the plume’s exit to the sea surface, and the velocity of bubble rise allows the gas dissolution process to be disregardded. The analysis was limited to almost calm hydrometeorological conditions. Such conditions are favourable for offshore operations, but unfavourable from the point of view of dispersion of high concentrations of oil product vapours in the near surface layer of the atmosphere. As a result of this work, an analytical dependence for an approximate assessment of the zone of intensive evaporation of gas condensate is proposed.

Keywords: emergency blowout of gas condensate wells, evaporation of gas condensate, the Arctic, mathematical modeling, zones of intense evaporation of gas condensate, oil spill response plans
Citation in English: Solbakov V.V., Zatsepa S.N., Ivchenko A.A. A mathematical model for estimating the zone of intense evaporation of gas condensate during emissions from shallow wells // Computer Research and Modeling, 2025, vol. 17, no. 2, pp. 243-259
Citation in English: Solbakov V.V., Zatsepa S.N., Ivchenko A.A. A mathematical model for estimating the zone of intense evaporation of gas condensate during emissions from shallow wells // Computer Research and Modeling, 2025, vol. 17, no. 2, pp. 243-259
DOI: 10.20537/2076-7633-2025-17-2-243-259
URL: http://crm-en.ics.org.ru/journal/article/3597/
Creative Commons License This work is licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License.

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